Re: Connecting Octave to the GUI

[John W. Eaton]

On 04/03/2013 06:48 PM, John W. Eaton wrote:
> For background info about what follows, please see the comments
> attached to this patch tracker entry:
>
> https://savannah.gnu.org/patch/index.php?7990
>
> Dan, I agree that the add/remove_X_hook functions are ugly.
>
> I checked in two changes that I hope will explain what I would like to
> do instead. They are here:
>
> http://hg.savannah.gnu.org/hgweb/octave/rev/70032fc70bee
> http://hg.savannah.gnu.org/hgweb/octave/rev/169f71c9d9c8
>
> The idea in those patches is to use the octave_link class more the way
> I think it was intended. Octave calls methods from this class to
> allow the GUI to handle things that happen in the interpreter like
> gathering input, entering/exiting the debugger, or calling the edit
> function at the command line. Since the octave_link class has pure
> virtual functions, it can't work by itself. So the GUI needs to
> provide some concrete implementation of those functions and we have
> the calls to the GUI that we need. By using this class, we have a
> clear definition of what Octave can ask the GUI to do.
>
> My plan is to replace the remaining hook functions that are registered
> in the octave_main_thread function with octave_link::calls instead.
> Then I'll add new methods for the dialog functions so specialized
> GUI versions can be called from the corresponding .m files. I still
> think it makes sense to do the argument decoding in the .m files.
>
> It would also be great if we can eliminate the octave_event_listener
> class (or at least reduce its usage to to whatever is really
> required for handling events while readline is waiting for input).

I checked in two more changes.

Then I noticed that the GUI was doing strange things when stepping in 
the debugger, including hitting errors while evaluating code and 
crashing randomly.  I don't think this is due to my latest changes.  I 
backed up to changeset 610e02bf9579 (prior to any of my octave-link 
changes) and although I haven't been able to trigger a crash yet, I am 
seeing evaluation errors when stepping.

If you'd like to try do duplicate this behavior, I'm able to trigger the 
errors by doing things like

  dbstop plot
  plot (rand (100,1), rand (100,1))

then either dbstepping rapidly at the command or with the step button on 
the editor.  You can step quickly at the command line by entering 
"dbstep" once, then hitting return repeatedly to repeat the previous 
debug command.

jwe